White Emitting ZnS Nanocrystals: Synthesis and Spectrum Characterization

Abstract

Spherical organic-bonded ZnS nanocrystals with 4.0±0.2 nm in diameter are synthesized by a liquid-solid-solution method. The photoluminescence spectrum of sample ([S 2− ]/[Zn 2+ ] = 1.0) shows a strong white emission with a peak at 490 nm and ∼ 170 nm full widths at half maximum. By Gauss fitting, the white emission is attributed to the overlap of a blue emission and a green-yellow emission, originating from electronic transitions from internal S 2− vacancies level to valence band and to the internal Zn 2+ vacancy level, respectively. After sealingZnS nanocrystals onto InGaN chips, the device shows CIE coordinates of (0.29,0.30), which indicates their potential applications for white light emitting diodes.

White light tunable emissions from ZnS: Eu3+nanophosphors over 330–465 nm excitation range for white LED applications

“…In this regard, nanocrystals of II-VI semiconductors such as CdS, CdSe and ZnS have been studied extensively as potential candidates for white light emitting phosphors (Nag and Sharma 2006, Gosnell et al 2006, Caifeng et al 2010. Among these compounds, ZnS nanophosphor is the most prominent candidate due to its strong absorption in the UV and blue region and its low toxicity (Huang et al 2010, Kuo et al 2010. Self-assembled nanocrystals have intrinsic disadvantages of self-absorption and sensitivity to thermal, chemical and photochemical changes.…”

“…Zinc sulfide based white light emitting phosphors are not new and different schemes have already been reported. Huang et al (2010) fabricated ZnS nanophosphor which emits broad band white light from UV-LED. These authors attributed the broad emission band to defect states of ZnS nanocrystals.…”